The anthracyclines of the daunorubicin group, such as doxorubicin, carminomycin and aclacinomycin and their synthetic analogs, are among the most widely employed agents in antitumoral therapy [F. Arcamone, Doxorubicin, Academic Press, New York, 1981, pp. 12-25; A. Grein, Process Biochem. 16:34 (1981); T. Kaneko, Chimicaoggi May:11 (1988); C. E. Myers et al., "Biochemical mechanisms of tumor cell kill". In: Anthracycline and Anthracenedione-Based Anti-Cancer Agents (Lown, J. W., ed.), Elsevier, Amsterdam, pp. 527-569, 1988; J. W. Lown, Pharmac. Ther. 60:185-214 (1993)].
The anthracyclines of the daunorubicin group are naturally occuring compounds produced by various strains of Streptomyces and Actinomyces carminata. Doxorubicin is mainly produced by S. peucetius subsp. caesius while daunorubicin is produced by S. peucetius, as well other Streptomyces, for example S. peucetius ATCC 27952 is described in U.S. Pat. No. 3,590,028, S. peucetius 29050 in U.S. Pat. No. 4,012,284, as well as the other Streptomyces.
In particular, the doxorubicin and daunorubicin are made by S. peucetius, ATCC 29050 and 27952 from malonic acid, propionic acid, and glucose by the pathway summarized in Grein, Advan. Appl. Microbiol. 32:203 (1987) and in Eckardt and Wagner, J. Basic Microbiol. 28:137 (1988). Aklavinone (11-deoxy-.epsilon.-rhodomycinone), .epsilon.-rhodomycinone and carminomycin are established intermediates in this process. The final step in this pathway in S. peucetius 27952 involves the hydroxylation of daunorubicin to doxorubicin [F. Arcamone et al., Biotechnol. Bioeng. 11:1101 (1969)].
Daunorubicin is known to be converted to 4'-O-glycosides called baumycins in Streptomyces species [Y. Takahashi, H. Naganawa, T. Takeuchi, H. Umezawa, T. Komiyama, T. Oki, and T. Inui. J. Antiblot. 30:622 (1977)].
Furthermore, the S. peucetius 29050 and 27952 strains usually produce much more .epsilon.-rhodomycinone than daunorubicin or doxorubicin. Since the therapeutically valueless .epsilon.-rhodomycinone cannot easily be converted to the important antitumor anthracycline drugs by chemical synthesis or biotransformation, it represents a commercially useless by-product of daunorubicin fermentations.
Up to now, several genes for daunorubicin and doxorubicin biosynthesis and resistance have been obtained from S. peucetius 29050 and S. peucetius 27952 by cloning experiments, but none of them were identified as conferring to their host the ability of converting .epsilon.-rhodomycinone into daunorubicin. ##STR1##